you can use it for 2-8 listeners. It would also allow the electronics to sit in a central location where the table/group leader could get it going without everyone touching it.
One like
this has two jacks on the receiving end so it can use a small headphone hole like in a boom box, computer or Kindle and a larger jack so it can go in older model cassette players and stereos...
You can get it with or without individual volume controls to save money but I recommend getting the individual one so it is one less thing to adjust on the main gadget.